Vim for C Programmers

You don't have to move to an integrated development environment to get luxury coding features. From variable autocompletions all the way up to integration with ctags and make, Vim makes a C programmer's life easier and more productive.

Vim and Syntax Highlighting

If there is one feature in Vim for which it wins
hands-down compared to any other editor or IDE,
it is full-featured syntax highlighting. The
colors available in Vim make it a veritable delight
to work with source code. It not only makes your life
colorful, it also makes it easy to spot errors ahead of
compilation. Common errors such as a mismatched ),}
or ] in the code are easy to see. It also
reminds you if you have left a string hanging without
the closing " or '. It tells you the comment doesn't
end with */, or that you are nesting comments. Syntax highlighting
is smart when it comes to C syntax.

Typically, you wouldn't have to do anything to enable Vim's syntax
highlighting; :sy on
does the job in case your distribution doesn't enable it by default. As with other commands, you can add this to your ~/.vimrc file.

If colors still don't show up, something is wrong with your terminal. Fix it first.
:se filetype on is another thing you can try in addition to
:sy enable.

Let us assume that you have colors displayed
correctly. Say you don't like a certain color, or
because blue is not visible in dark backgrounds, you can't read C comments.
To solve the second problem, a simple
:se background=dark
does the job. If you want to disable syntax highlighting for C comments, type
:highlight clear comment.

To change colors, first use the
:syntax
command to display all the syntax items for the given buffer. Then,
identify the syntax group you want to change. If
you want strings displayed in a bright white
color, which is easy to read against a black background, simply enter:

:highlight String ctermfg=white

or, for gvim users, type:

:highlight String guifg=white

You also can change the syntax color of any
group. Typical syntax groups are Statement, Label,
Conditional, Repeat, Todo and Special. You
can change the attributes of highlighting as well, such as
underline and bold. For instance, if you want
to display NOTE, FIXME, TODO and XXX with underlining,
you can use:

:highlight Todo cterm=underline

or you can both add bold and change the color:

:highlight Repeat ctermfg=yellow cterm=bold

You can create your own set of highlight commands
and save it in your ~/.vimrc file so that every time
you edit your source code, your favorite colors
are displayed.

Vim and Variable Name Completion

In addition, Vim has a feature for variable name completion. While
typing, simply press Ctrl-N or Ctrl-P in insert
mode. Remember, this works only in insert mode. All
other commands mentioned above work in command
mode. You can cycle through possible completions by
pressing Ctrl-N again.

This helps us avoid errors while typing, because
structure members and function names often can be
misspelled. This works best when Vim can use tags,
so make sure a ctags file is in place.

Vim and Source Code Formatting

Vim understands C well enough to be able to indent code automatically.
The default indentation style uses tabs, which may not be appropriate for some people.
In order to remove tabs completely from the source, enter:

:set expandtab
:retab

which converts all tabs into spaces in such a way
that the indentation is preserved. While typing C
text, Vim automatically indents for you. This
helps you figure out where you have your matching
brace. You can match braces, ), ] and } with the %
command in command mode. Simply take the cursor
to a brace and press %, which takes you to the
corresponding closing or opening brace. This works
for comments as well as for #if, #ifdef and #endif.

After finishing typing the program, if you want to indent the whole file
at one go, type gg=G in command mode. You then can
remove tabs if you want by the above-mentioned method.
gq is the command sequence for indenting comments.
You can select a region and indent it too with the = operator.

If Vim's default tab indentation is painful to use, you can disable
it by setting :se nocindent. Other indentation
options are available. You can indent
code between two braces and between certain line
numbers. You can learn more by typing :help
indent.txt.

I just wanted to add, for those who are new to vim, that most of the settings like "se nu" can be made to persist across logins by just putting that setting in .vimrc file in the user's home directory.